Portable grinding and polishing machine



June 19, 1928.

1,613,909 F. S. GEPHART PORTABLE GRINDING AND POLISHING MACHINE Filed Jan. 19, 1925 g/um: (TY/41447 Patented June 19, 1928 1 1,673,909 PATENT OFFICE.-

FRANK S. GEPHART, OF DOVER, OHIO.

PORTABLE GRINDING AND POLISHING MACHINE.

Application filed January 19, 1925. Serial No. 3,310.

This invention relates to grinding and polishing machines, and more particularly to a portable machine especially designed for grinding stairs of terrazzo, cement or the like, and provided with an attachment for grinding vertical surfaces such as bases, side-walls and the like.

The objects of the invention are toprovide a grinding and polishing machine which may be placed upon the stair-step to be ground, and containing a motor driven grinding wheel arranged to contact with the surface of the step, handles being provided upon the machine for guiding the same to move the grinding wheel over the entire surface of the step; an attachment being provided for grinding vertical surfaces such as bases and the like, and arranged to be operatively connected to the driving mechanism of the machine by a flexible shaft; means being provided for attaching a drill to the flexible shaft to drill holes in slabs of marble, cement or the like. a

The above and other objects may be attained by constructing the grinding and polishing machine in the manner illustrated in the accompanying drawing, in which:

Figure 1 is a top plan view of a machine embodying the invention, parts being broken away for the purpose of illustration;

Fig. 2, a vertical longitudinal section on the line 22, Fig. 1;

Fig. 3, an elevation of the flexible shaft and attachment for grinding bases and the like;

Fig. 4, a front elevation of the grinding attachment. and,

Fi 5, a fragmentary elevation, partly in sectio n, of the socket portion of the flexible shaft and the drill adapted to be attached.

thereto.

Similar numerals of reference indicate corresponding parts throughout the drawing.

The machine is supported upon a frame, preferably cast of aluminum, and comprising the enlarged portion 1 forming a casing for the motor 2 and the reduced, elongated portion 3 forming a casing for the shaft 1. Bearings 5 are provided at each end of the shaft casing portion and contain bushings 6 in which the shaft is journaled, oil holes being provided for said bearings as shown at 7.

The shaft 4 may be operatively connected to the motor shaft 8 in any usual and well known manner such as the pinion 9 upon the motor shaft and the pinion'lO, upon the shaft 1, and meshing with the pinion 9.

A removable cover 11 may be provided for the motor casing, and a cover plate 12 may be detachably mounted upon the shaft casing 3 to shield the parts from the dust and grit which is naturally encountered in the work for which the machine is intended.

Casters 13 are provided beneath the motor casing, and a removable caster 14 is attached ncarthe outer end portion of the shaft casing whereby the machine may be easily moved to and fro upon the floor or other surface. For the purpose of guiding the machine ahandle 15 is provided upon the motor casing, and a similar handle 16 upon the cover plate of the shaft casing.

The outer endof the shaft 4 is provided with a reduced shank 17 to receive a tapered grinding wheel 18 or the like, the extremity of said shank being threaded as shown at 19 for the reception of a nut 20 which cooperates with a washer 21, located in the countersunk end 22 of the grinding wheel, to retain the grinding wheel rigidly upon the shaft.

In using the machine to grind the surface of stair-treads, the detached caster 14: is removed and the machine placed upon the tread to be ground and polished,the motor portion of the machine being supported uponthe casters 18 while the periphery of the grinding wheel 18 contacts with the surface to be ground. The operator grasps the handles 15 and 16 and moves the machine over the surface of the stair-tread, the grinding wheel and casters 13 remaining in contact with the sljirface to be ground, the operator guiding the grinding wheel over all portions of the surface to properly grindand polish the same.

For the purpose of grinding vertical surfaces such as bases and the like, grinding wheel 18 is removed from the shank 17 and the swivel. socket 23 of the flexible shaft 24: is connected to said shank. The flexible shaft is provided at its outer end with a shank 25 having a shoulder 26 intermediate its extremities and terminating in a. threaded portion 27.

The attachment for grinding bases and the like comprises a disk 28 adapted to be secured upon the threaded portion 27, and provided with a plurality of blocks 29 of earborundum or the like, theflat surfaces of which are adapted to engage the base or other vertical surface to be ground and vpolished. In using this attaclnnent; the caster 14 is attached to the machine, pern'litting the same to be easily moved over the tloor to 'l'ollow the operator as he grinds the surface of a base or the like.

A socket 30 may be provided in the outer end of the shank whereby a drill such as indicated at 31 may be attached to the flexible shaft and secured against rotation thereon as by the set screw 32, providing means for drilling holes at any desired location in slabs of marble, cement or the like.

Various forms of grinding tools may be connected to the flexible shaft, such as the grinding wheel 18 or the like, although for most; purposes it will be seen that a tool sue-h as the attachment 28 is preferable for grinding llat vertical surfaces of bases or the like.

From the above it will be obvious that, in the operation of the machine the electric motor 2 will drive the shaft; 4: through the gears 9 and 10, rotating the grinding wheel 18 or the flexible shaft 24 at a high rate of speed to quickly and uniformly grind and polish the surfaces of the stair-treads, bases, etc. As the machine is ol suitable proportions to permit it to be placed directly upon the surl'aee ol the step to be ground, it, will be seen that the operator may move the machine, during the grindingera-ration, to grind all parts oi? the surface.

I claim:

A portable surt'aee grinding machine including a frame forming a motor casing and an elongated substai'itially horizontal shatt- 

